An indicator light conventionally comprises a filament lamp mounted on a back plate which constitutes its base, together with an optic or cover glass in front of the lamp. Optical means are frequently used for directing a major proportion of the light emitted by the lamp into a direction which is close to a preferential emission axis, or else to confer a homogeneous light intensity on the lighting field of the indicator light in the event that a light source is used which is essentially a light source giving an intense light output.
It is also known to provide an indicator light which is subdivided into a plurality of elements, each of which includes a small filament lamp, for example a lamp of the wedge base type, in cooperation with its own optical means, the object of this being to obtain a field of light which is both homogeneous and of large extent, while the light unit itself is of reduced thickness. Such a light, having a plurality of lamps, is however expensive to make.
More generally, the various components of an indicator light, with the exception of the lamp or lamps (which are generally standard) must be subjected to scrutiny and specific development (in every case, in accordance with a given specification). This results in a relatively high selling price.
Other disadvantages of conventional indicating lights or light units lie in the fact that the filament lamps which are used have to be replaced quite frequently, and they generally occupy a substantial depth, due to the fact that the base on which they are fitted must present (at least with some lamps) a parabolic profile for light flux concentration. Yet another disadvantage is that it is impossible to produce fields of light with complex contours. In connection with this last point, the designer generally has to work with simple circular or rectangular shapes only.
Finally, it is known from the specification of European published patent application EP 0 328 088A, to provide a light which has a frame in which a plurality of individual modules are grouped. Each of these modules comprises a support in which a light emitting diode is fitted. In this known arrangement, the modular character of the light is limited to the light sources themselves, so that the designer still has only very limited scope for flexibility in design.